Inpatient and outpatient therapy often requires the administration of an intravenous solution to a patient through a device such as a catheter to permit infusion of medicament or other solution as required. The rate of flow of solution into the patient's body is an extremely important variable which can be affected by the pressure of the solution supply and the fluid viscosity.
It is present practice to use a capillary type flow restrictor which includes a relatively long, small diameter tube (on the order of 0.0015 inches) in order to regulate the flow of medicament or solution to the patient. However, capillary type flow restrictors are inherently problematic. First, because of the nature of the device, the upstream pressure, or the solution pressure, will have a great affect on the rate of flow of solution through the capillary. Second, the fluid viscosity also greatly affects the rate of flow through the capillary. As such, when the viscosity of the fluid increases, the rate of flow of solution or medicament decreases.
Because of the inherent nature of capillary type flow restrictors, in order to maintain a constant flow rate through the capillary, either the solution feed pressure has to be maintained at a constant level or the fluid viscosity, vis-a-vis fluid temperature, must be maintained at a constant level. As a result, to effectuate the proper solution feed to a patient, the patient is required to be relatively immobile to assure that the fluid conditions, i.e., solution feed pressure and viscosity, remain at the required levels.
The present invention contemplates a highly accurate solution feed system which comprises a solution feed container, a tubing set and an orifice flow restrictor. The orifice flow restrictor operates in a manner which is relatively independent of the solution feed pressure and viscosity, therefore making it much more advantageous for use in both inpatient and outpatient application for continual solution or medicament feed to a patient.